1. Field of Invention
The present invention is directed to multi-band antennas. In particular, the present application is directed to a planar inverted-F antenna with selectable frequency responses.
2. Description of Related Art
Presently, devices such as mobile communication devices utilize antennas such as planar inverted-F antennas (PIFAs) for the transmission and reception of radio frequency (RF) signals. These mobile communication devices require the capability to transmit in various frequency bands to be compatible with various systems. For example, such systems can operate at 800, 900, 1800, and 1900 MHz. Unfortunately, at best, current antennas used in mobile communication devices can only operate in limited frequency bands. For example, current PIFA antennas can only operate in a dual band and are incapable of operating for more than two frequency bands. Another problem exists in that present antennas for mobile communication devices have limited bandwidth of operation. A further problem exists in that increasing power to present antennas for improved performance results in specific absorption ratio problems.
Thus, there is a need for an antenna assembly that provides for multiple frequency operation over a wide bandwidth while reducing specific absorption ratio problems.
The invention provides an antenna assembly for a mobile communication device. The antenna assembly can include a RF connection feed point and a planar radiating element including a conductive area split by a nonconductive gap which divides the planar radiating element into a first arm having an end coupled to the RF connection feed point and a second arm having an end coupled to the RF connection feed point. The antenna assembly can also include a first connection point coupled to the opposite end of the first arm from the RF connection feed point, the first connection point being selectively coupled to an impedance.
According to another embodiment, the invention provides an antenna assembly for a mobile communication device, including a RF connection feed point, a first arm having an end coupled to the RF connection feed point, a second arm having an end coupled to the RF connection feed point, and tuning circuitry selectively coupled to the opposite end of the first arm from the RF connection point. The tuning circuitry can be a first connection point selectively coupled to a ground. The tuning circuitry can also be an impedance. The antenna assembly can also include means for selectively eliminating the effects of the second arm on the antenna assembly. The means for selectively eliminating can be an impedance coupled to the opposite end of the second arm from the RF connection point. Also, the means for selectively eliminating can be a second connection point coupled to the opposite end of the second arm from the RF connection point, the second connection point being selectively coupled to a ground.
The antenna assembly can also include a connection leg in close proximity to the RF connection feed point, the connection leg being selectively coupled to a ground. The second arm can be longer than the first arm or the first arm can be longer than the second arm. The first arm can include a section folded substantially perpendicular to the first arm along a length of the first arm. Also, the first arm can include a section folded substantially perpendicular to the first arm at the end of the first arm, wherein the tuning circuitry can be coupled to the section folded substantially perpendicular to the first arm. Furthermore, the second arm can include a section folded substantially perpendicular to the second arm at the end of the second arm.
Thus, the present invention solves numerous problems with present antennas and provides additional benefits that are apparent in the description below.